The invention relates to the resumption of movement after unforeseen stopping in an automated parking process by means of a parking assistance system having automated longitudinal and transverse guidance.
In parking assistance systems having automated transverse guidance, the steering of the vehicle is controlled by the system during the parking-space-entering process. The longitudinal guidance has to be performed by the driver himself by corresponding acceleration and braking. In parking assistance systems having automated transverse and longitudinal guidance, the task of longitudinal guidance is also performed by the parking assistance system; the longitudinal movement of the motor vehicle is controlled by the parking assistance system. In parking assistance systems with transverse guidance and longitudinal guidance, the steering, the brakes and the vehicle drive are therefore controlled by the parking assistance system. In such parking assistance systems having automated transverse and longitudinal guidance, the driver generally has the possibility of being able to have the vehicle placed automatically in a parking space and optionally removed therefrom by activating an operator control element in the vehicle cockpit.
An exemplary parking assistance system having automated transverse and longitudinal guidance is described in document “Parkassistent mit Längs-und Querführung [Parking assistant with longitudinal and transverse guidance]”. Dirk Ahrens, 5th conference for driver assistance at the TU München [Technical University of Munich], Munich, 2012, which can be found on the Internet, for example, at the link http:/www.ftm.mw.tum.de/uploads/media/21_Ahrens.pdf. When a vehicle is manually passing parked vehicles, a suitable longitudinal parking space is found by use of a lateral sensor system and said parking space is displayed visually to the driver on a display in the vehicle. The driver then confirms the parking space which has been found. If the driver is located in a valid starting corridor next to the front boundary object, from which there is a possible driving trajectory into a valid final parked position, the parking maneuver is activated by pressing and holding down a parking button and subsequently releasing the brake. After the parking maneuver has been activated, the vehicle parks backwards under automatic control of the steering and automatic control of the longitudinal movement into the longitudinal parking space in one or more maneuvering movements.
Between two successive maneuvering movements of the parking-space-entering trajectory there is in each case what is referred to as a reversal point (also referred to as a switching point) at which the direction of travel is changed from rearward to forward or from forward to rearward. In this respect, at the respective switching point the vehicle is automatically brought to a standstill by automatic activation of the brakes and the vehicle carries out a change of gear in the automatic transmission in order to change the direction of travel after the stationary state has been reached.
The parking-space-entering trajectory is planned after measurement of the parking space and results in one or more planned reversal points and a planned final parked position; it is also contemplated for the final parked position to be reached in a single maneuvering movement and for no reversal point to be included in the planning. Ideally, the vehicle carries out the trajectory as planned and stops briefly at the planned switching point in order to carry out a change of gear.
The vehicle can, however, also come to a standstill in an unforeseen way when the parking-space-entering trajectory is travelled along, for example in the event of interruption by the driver or in the event of an increased driving resistance.
The object of the invention is to improve the resumption of movement of the vehicle after it comes to a standstill in such an unforeseen way.
The object is achieved by a method for resuming the movement of a motor vehicle after unforeseen stopping in an automated parking process, as well as a parking assistance system having automated longitudinal and transverse guidance that carries out the method, in accordance with embodiments of the invention.
A first aspect of the invention relates to a method for resuming the movement of a motor vehicle after unforeseen stopping in an automated parking process, in particular in a reversing process for entering a longitudinal parking space (parallel to the direction of the road) by use of a parking assistance system with automated longitudinal and transverse guidance.
According to the method, in the event of the vehicle stopping, a decision is made about a resumption of movement of the vehicle in the previous direction of travel which existed before the vehicle was stopped. The decision is made according to a preferred refinement of the invention as a function of the remaining route from the current position up to the next planned stopping point, in the previous direction of travel, on the trajectory. A stopping point on the trajectory can be, for example, a reversal point or the final parked position. In the event of a positive decision, the movement of the vehicle is resumed in the previous direction of travel. In the event of a negative decision, the movement of the vehicle is resumed counter to the previous direction of travel. Alternatively, it is also contemplated that in the event of a negative decision the movement of the vehicle is not resumed and the parking process is ended.
The method according to the invention makes it possible to prevent a situation in which when the vehicle comes to a standstill in an unforeseen fashion shortly before a planned stopping point, the parking assistance system resumes the movement of the vehicle for a short distance in order then to initiate the change of direction of travel in the case of a reversal point as the stopping point, or to output the final position as having been reached in the case of the final parked position as a stopping point. As result, situations which are implausible from the driver's point of view can be avoided with a brief resumption of movement after the vehicle has come to a stationary state in an unforeseen fashion.
Alternatively or additionally, a decision about the resumption of movement of the vehicle in the previous direction of travel can also be made as a function of the presence of any obstacle in the previous direction of travel. If, for example, the previous direction of travel is blocked by an obstacle, the system automatically carries out a change of direction of travel and continues the parking maneuver in the opposite direction of travel.
The decision is preferably made as a function of the remaining route from the current position up to the next planned reversal point, in the previous direction of travel, on the trajectory, wherein in the event of a negative decision, the movement of the vehicle is started counter to the previous direction of travel.
In the case of stopping before the final parked position, the decision is made as a function of the remaining route from the current position up to the final parked position of the trajectory (if there is no planned reversal point between the current position and the final parked position on the trajectory). In the event of a negative decision, the movement of the vehicle is not resumed and the vehicle ends the parking process.
In order to make a decision about a resumption of movement of the vehicle in the previous direction of travel, a threshold value comparison of the remaining route from the current position up to the next planned stopping point, in the previous direction of travel, on the trajectory is preferably made with a threshold value which is greater than zero (for example 10 cm).
Within the scope of the threshold value comparison it is preferably checked whether the remaining route from the current position up to the next planned stopping point, in the previous direction of travel, on the trajectory is less than or less than or equal to the threshold value.
In the event of the remaining route being less than or less than or equal to the threshold value, the movement of the vehicle preferably counter to the previous direction of travel is started (if the vehicle stops just before a reversal point), or the movement of the vehicle is not resumed and the parking process is ended (if the vehicle stops just before the final parked position).
The threshold value is preferably in the range from 30 cm to 5 cm. The threshold value corresponds, for example, approximately to the value of 10 cm.
According to one further embodiment of the method, the method is used in a process of reversing into a longitudinal parking space. Within the scope of the method it is checked whether the vehicle has reached or passed a specific point on the parking-space-entering trajectory of the first maneuver movement for entering a parking space in the reverse direction. In the event of any obstacle being present in the previous direction of travel, the movement of the vehicle is resumed counter to the previous direction of travel if the specific point on the parking-space-entering trajectory has been reached or passed. The point on the parking-space-entering trajectory of the first maneuver movement for entering a parking space preferably corresponds to the point starting from which or after which an acceptable final parked position can be reached in the event of the movement being resumed counter to the previous direction of travel.
A second aspect of the invention relates to a parking assistance system having automated longitudinal and transverse guidance. The parking assistance system is configured to make a decision, in the event of unforeseen stopping in an automated parking process, about resumption of the movement of the vehicle in the previous direction of travel which existed before the vehicle was stopped. The decision is preferably made as a function of the remaining route from the current position up to the next planned stopping point, in the previous direction of travel, on the trajectory. The decision can alternatively or additionally be made as a function of the presence of any obstacle in the previous direction of travel. In the event of a positive decision, a resumption of the movement of the vehicle in the previous direction of travel is brought about by the system. In the event of a negative decision, a resumption of movement of the vehicle counter to the previous direction of travel is brought about or no resumption of movement is brought about (in either of the two directions of travel) and the parking process is ended.
The above statements regarding the inventive method according to the first aspect of the invention apply correspondingly also to the inventive parking assistance system according to the second aspect of the invention. At this point, advantageous exemplary embodiments of the system according to the invention which are not described explicitly correspond to the described advantageous exemplary embodiments of the inventive method.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawing.